Electro-L is an approved geostationary meteorological mission under development of ROSHYDROMET / PLANETA / Roscosmos (Russian Federal Space Agency), a successor spacecraft to GOMS (Geostationary Operational Meteorological Satellite), also referred to as Electro-1, launched Oct. 31, 1994 (which was never brought to full operational service due to technical problems). The overall mission objectives of Electro-L are:

• To provide on an operational basis multispectral imagery (hydro-meteorological data) of the atmosphere (including the cloud-covered sky) and of the Earth's surface within the coverage region (visible disk) of the spacecraft

• To collect heliospheric, ionospheric, and magnetospheric data

• To provide the needed communication services for the transmission/exchange of all data with the ground segment

• To provide the services of data collection for the DCPs (Data Collection Platforms) in the ground segment as well as to provide the services of COSPAS/SARSAT.

The Electro-L spacecraft is being designed and built by NPO Lavochkin Research and Production Association of Moscow. The spacecraft employs the so-called "navigator" platform, a general purpose bus which is three-axis stabilized. A pointing accuracy of < 0.05º is provided; the angular drift is < 5 x 10-4 º/s. A deployable solar array provides a power of 1.7 kW (EOL, the mean power consumption of the S/C is about 700 W). The total mass of the spacecraft is about 1500 kg (payload mass of 370 kg). The S/C design life is 10 years. 1)2)3)4)5)

Figure 2: Illustration of the Electro-L spacecraft and some of its components (image credit: Roshydromet/Planeta)

Launch: The Electro-L No 1 spacecraft was launched on January 20, 2011 on a Zenit-2 launch vehicle with a Fregat-SB booster from the Baikonur Cosmodrome, Kazakhstan. 6)7)

Orbit: Geostationary orbit at the nominal location of 76º East (in the equatorial plane over the Indian Ocean).

OREC (Onboard Radio Engineering Complex). The objectives of the RF communication system are to provide all data transmission, relay, and retransmission services with the ground segment. These consist of the following functions:

• The sensor data downlink to CPPI (Ground Acquisition and Distribution Center) is in X-band (7.5 GHz) at a data rate of 2.56-15.36 Mbit/s

• Data reception from ground segment DCPs at 400 MHz (UHF), or DCP data relayed via LEO satellites at a frequency of 470 MHz. This data is transmitted from Electro-L to the CPPI in S-band at 1.7 GHz.

• Onboard reception of processed hydro-meteorological data products in X-band (8.2 GHz) and relay of this data in HRIT LRIT and WEFAX formats (in S-band at 1.7 GHz) to all customers

• Exchange of hydro-meteorological data and remote sensing data between regional centers in X-band (at 8.2 and 7.5 GHz) with data rates of up to 15.36 Mbit/s

• Data reception of COSPAS-S&RSAT messages at 406 MHz and retransmission of these messages at 1.54 GHz.

• In April 2015, the status of the Electro-L No 1 mission was identical to that stated in November 2015. 11)

• Nov. 14, 2014: The Electro-L spacecraft is in geostationary orbit at location 76ºE over the equator and continues to be used for its intended purpose with some restrictions. The orientation of the satellite is performed with stabilization engines. Even after the introduction of restrictions, the satellite camera provides monitoring of the visible disk of the Earth. 12)

- The multispectral camera (MSU-GS) of Electro-L provides the pre-programmed ability to capture images of the Earth in 10 ranges of visible and thermal infrared regions of the spectrum.

- The onboard equipment provides data on geophysical conditions in near-Earth space, performs telecommunications functions as well and to relay heliogeophysical data and information from the data-collection-platforms and ground units of the COSPAS-SARSAT system.

• The Electro-L spacecraft and its payload are operating nominally in 2014. 13)14)

• The Electro-L spacecraft and its payload are operating "nominally" in 2013 after more than 2 years on orbit (there is still a problem with the MWIR and TIR channels). 15)16)17)

Legend to Figure 7: Unlike most satellite images of Earth, this one was not assembled from multiple swath scans or digitally projected onto a globe model — it's the full disk of our planet captured as a single, enormous 121 megapixel image, acquired by Russia's Elektro-L weather-forecasting satellite.

Unlike NASA/NOAA GOES satellites, Elektro-L captures images in the infrared (MWIR, TIR) as well as in the VNIR spectrum, providing detail about not only cloud movement but also vegetation variations. Its wide-angle MSU-GS (Multichannel Scanning Unit-Geostationary) imager takes images every 15-30 minutes, showing the same viewpoint of Earth across progressive times of the day.

• The commissioning phase ended in December 2011. Nominal operations of Electro-L were started in January 2012. The imager (MSU_GS) is providing images to Planeta and NTs OMZ (Research Center for Earth Operative Monitoring) every 15 minutes. The geophysical system (GGAK-E) is operational as well. 20)

• In mid-July 2011, Roskosmos announced that the testing of systems onboard the Elektro-L satellite had entered its final stage, while the trials of its ground control segment were still ongoing. Specialists were conducting test evaluation of the satellite's imagery and had completed a 10-day cycle of continuous photography. Updates to the algorithms of the image-processing software had been underway based on the produced test imagery, the agency said (Ref. 8).

• Several months into the mission, it was revealed that Elektro-L did experience a failure of one of four gyroscopic attitude control channels immediately after the launch. Although, the problem was reportedly compensated with the use of onboard sensors, the launch of the Spektr-R space observatory, which used a similar system, had to be delayed (Ref. 8).

• The Electro-L spacecraft is in the commissioning phase as of March 2011.

• The solar array deployed right after the spacecraft reached its target orbit.

MSU-GS is a 10-channel radiometer.The instrument is being designed and developed by FSUE/RISDE (Federal State Unitary Enterprise) / Russian Scientific Institute of Space Device Engineering), Moscow, Russia (note: the Russian abbreviation of FSUE/RISDE is RNIIKP).

The objectives are to obtain solar reflected imagery and brightness temperature measurements from TOA (Top of Atmosphere) and of the Earth's surface (ocean and land). In addition, the tropospheric moisture content is determined. An image of a sub-region of the disk of size yy km x zz km can be obtained in parallel. The instrument data rate is 2.56 - 15.36 Mbit/s. 22)23)

The MSU-GS instrument is a multi-zonal scanner to take imagery in 3 visible and 7 infrared bands. In full accordance with specifications of ROSHYDROMET, MSU-GS parameters will be close to those of the SEVIRI (Spinning Enhanced Visible and Infrared Imager) instrument now operating onboard the MeteoSat-8/MSG-1 spacecraft of EUMETSAT.

The objective of this instrument suite is to obtain particles (particle count of protons, electrons and alpha particles), to measure the sun's X-ray radiation, the solar constant, and to measure the magnetic field components for: 24)

• Monitoring and forecasting of solar activity

• Monitoring and forecasting radiation and magnetic field in the near-Earth space

• Diagnostics and monitoring of the natural and modified magnetosphere, ionosphere and upper atmosphere.

FM-E, the digital ferro-sonde magnetometer, measures three components of the magnetic induction vector. It consists of a 3-component ferro-sonde sensor, a 3-channel analog electronic unit, a digital data collection system on the basis of sigma-delta modulators, and an isolated secondary power supply source.

Magnetic induction range (for each component)

±600 nT

Temperature coefficient

10-5

Null level

within ±5 nT

Relative accuracy

0.01%

Measurement (or sampling) rate

16 vectors/s

Working temperature range
- Sensor unit
- Electronic unit

-60º to +60º
0 to 40º

Power consumption

< 3 W

Instrument size
- Sensor unit
- Electronic unit

65 mm x 65 mm x 100 mm
75 mm x 155 mm x 225 mm

Instrument mass

0.5 kg (sensor unit), 2.5 kg (electronic unit)

Working resource

> 120,000 hours

Failure-free operation probability

> 0.95

Table 4: Main FM-E instrument parameters

ODSS (Onboard Data Sampling System):

ODSS is a data collection system provided by ROSHYDROMET, Moscow.

GEOSAR (Geostationary Search & Rescue) system:

GEOSAR is of COSPAS-S&RSAT for emergency calls. The repeater is redundantly configured and consists of the following units: 25)

The 406 MHz signals from 406 MHz beacons are received by the antenna and fed through the diplexer and switch to a low-noise amplifier. The low-noise amplifier output is connected to the S&R receiver. The signal is down-converted for bandpass filtering in accordance with one of two commandable band with modes; a narrow band mode of 20 kHz or a wide band mode of 80 kHz.

The filtered output signal is further down-converted to the near baseband and fed through amplifiers to the S&R transmitter. The overall gain of the S&R receiver can be command selected into a fixed gain or Automatic Gain Control (AGC) mode.

The S&R transmitter phase modulates the signal 1544.5 MHz and amplifies the modulated carrier to 4 W. The phase-modulated signal has the nominal modulation index set such that the carrier suppression is 3 dB with the receiver in the AGC mode. A baseband limiter restricts the modulation index from exceeding 2 radians. The transmitter output is applied through a 4 MHz bandwidth filter to antenna.

Note: Throughout this documentation the terminology of GEOSAR and S&RSAT are being used instead of the "GEOSAR" and "SARSAT" terms (as introduced in the literature) - in order to avoid confusion with the acronym SAR (Synthetic Aperture Radar) which is frequently being used in Earth observation programs.

• The S&R receive antenna is right-hand circularly polarized (RHCP) with an on-axis gain of 15 dB including line loss. The receive antenna has a maximum axial ratio of 3 dB

• The S&R transmit antenna is also RHCP with an on-axis gain 14 dB including line loss. The transmit antenna has a maximum axial ratio of 3 dB.

The GEOSAR repeater receives 406 MHz beacon signals within the field of view of the 406 MHz receive antenna beam. The beacon signals are processed by the repeater and transmitted on the downlink signal for reception by a GEOLUT (Geostationary Local User Terminal).

The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (herb.kramer@gmx.net).